TORONTO -- Canada's confirmed number of swine flu infections rose to 19 after the diagnoses of three Toronto-area women who returned from Mexico, health officials said.

By province Thursday, there were seven cases in Ontario, six in British Columbia, four in Nova Scotia and two in Alberta, the Canadian Broadcasting Corp. reported.

Federal and provincial health officials said all of the cases are considered mild. Their various Web sites and public broadcasts all urge people with symptoms of any illness to quarantine themselves at home and to wash hands frequently.

However, Chief Public Health Officer Dr. David Butler-Jones discouraged healthy Canadians from wearing face masks, in part to keep the fear factor down, Sun Media reported.

"Our research shows that wearing masks does very little to reduce the spread of infection in the general population and that improper use may actually increase your risk of getting ill," Butler-Jones said.

He said masks need only be worn by those who are ill and their medical caregivers, the report said.